4,816 research outputs found
Chemical and biological investigations of Delonix regia (Bojer ex Hook.) Raf.
U radu je opisana izolacija pet sastojaka petroleterske i diklormetanske frakcije metanolnog ekstrakta kore biljke Delonix regia: lupeol (1), epilupeol (2), β-sitosterol (3), stigmasterol (4) i p-metoksibenzaldehid (5). Nadalje, testirano je antimikrobno djelovanje različitih ekstrakata difuzijskom metodom na disku (15 μg mm2). Zone inhibicije za sastojke topljive u petroleteru, tetraklormetanu i diklormetanu bile su 914 mm, 1113 mm, odnosno 920 mm, dok je zona inhibicije standarda kanamicina bila 2025 mm. U biološkom pokusu smrtnosti morskih kozica najveću toksičnost pokazali su spojevi topljivi u tetraklormetanu (LC50 = 0,83 μg mL1), dok je topljivost sastojaka topljivih u petroleteru i diklormetanu bila LC50 14,94, odnosno 3,29 μg mL1, a standarda vinkristin sulfata 0,812 μg mL1. Ovo je prvo izvješće o izolaciji sastojaka, antimikrobnom djelovanju i citotoksičnosti biljke D. regia.In this study five compounds, lupeol (1), epilupeol (2), β-sitosterol (3), stigmasterol (4) and p-methoxybenzaldehyde (5) were isolated from the petroleum ether and dichloromethane fractions of a methanolic extract of the stem bark of Delonix regia. Antimicrobial screening of the different extracts (15 μg mm2) was conducted by disc diffusion method. The zones of inhibition demonstrated by the petroleum ether, carbon tetrachloride and dichloromethane fractions ranged from 914 mm, 1113 mm and 920 mm, respectively, compared to kanamycin standard with the zone of inhibition of 2025 mm. In brine shrimp lethality bioassay, the carbon tetrachloride soluble materials demonstrated the highest toxicity with LC50 of 0.83 μg mL1, while petroleum ether and dichloromethane soluble partitionates of the methanolic extract revealed LC50 of 14.94 and 3.29 μg mL1, respectively, in comparison with standard vincristine sulphate with LC50 of 0.812 μg mL1. This is the first report on compounds separation from D. regia, their antimicrobial activity and cytotoxicity
Light propagation through closed-loop atomic media beyond the multiphoton resonance condition
The light propagation of a probe field pulse in a four-level double-lambda
type system driven by laser fields that form a closed interaction loop is
studied. Due to the finite frequency width of the probe pulse, a
time-independent analysis relying on the multiphoton resonance assumption is
insufficient. Thus we apply a Floquet decomposition of the equations of motion
to solve the time-dependent problem beyond the multiphoton resonance condition.
We find that the various Floquet components can be interpreted in terms of
different scattering processes, and that the medium response oscillating in
phase with the probe field in general is not phase-dependent. The phase
dependence arises from a scattering of the coupling fields into the probe field
mode at a frequency which in general differs from the probe field frequency. We
thus conclude that in particular for short pulses with a large frequency width,
inducing a closed loop interaction contour may not be advantageous, since
otherwise the phase-dependent medium response may lead to a distortion of the
pulse shape. Finally, using our time-dependent analysis, we demonstrate that
both the closed-loop and the non-closed loop configuration allow for sub- and
superluminal light propagation with small absorption or even gain. Further, we
identify one of the coupling field Rabi frequencies as a control parameter that
allows to conveniently switch between sub- and superluminal light propagation.Comment: 10 pages, 8 figure
Gambaran Kristal Hemoglobin pada Bercak Darah yang Terpapar pada Beberapa Zat Pembersih Lantai Domestik Non Karbol
Bloodstain is an evidence that often found in criminal case. Bloodstain which is found on a crime scene often already contaminated, there might be an effort to clean up the bloodstain on the floor by using floor cleaner agents. The exposure of cleaning agents potentially damaging membrane cell and denature protein inside the blood, so at the time when forensic examination of bloodstain has been done it is possible to generate different interpretations. This research is a descriptive research with experimental laboratory design to find out the description of haemoglobin crystal on bloodstain exposed by some non carbolic domestic floor cleaner agent using Teichmann test and Takayama test. This research shows that haemoglobin crystal can be found on eighty slide of bloodstain which has been flowed and swabbed by non carbolic domestic floor cleaner agents. The conclusion of this research is no effect of the exposure by non carbolic domestic floor cleaner agent against haemoglobin crystal description on the Teichmann and Takayama test
Spontaneous emission by rotating objects: A scattering approach
We study the quantum electrodynamics (QED) vacuum in the presence of a body
rotating along its axis of symmetry and show that the object spontaneously
emits energy if it is lossy. The radiated power is expressed as a general trace
formula solely in terms of the scattering matrix, making an explicit connection
to the conjecture of Zel'dovich [JETP Lett. 14, 180 (1971)] on rotating
objects. We further show that a rotating body drags along nearby objects while
making them spin parallel to its own rotation axis
Potentiometric Determination of Ketotifen Fumarate in Pharmaceutical Preparations and Urine Using Carbon Paste and PVC Membrane Selective Electrodes
This study compares
between unmodified carbon paste (CPE; the paste
has no ion pair) and polyvinyl chloride (PVC)
membrane selective electrodes that were used in
potentiometric determination of ketotifen
fumarate (KTF), where sodium tetraphenylborate
(NaTPB) was used as titrant. The performance
characteristics of these sensors were evaluated
according to IUPAC recommendations which reveal
a fast, stable, and linear response for KTF over
the concentration range of 10−7 to
10−2 mol L−1. The
electrodes show Nernstian slope value of
52.51 ± 0.20 and 51.51 ± 0.25 mV decade−1 for CPE and PVC membrane
electrodes at 30°C, respectively. The potential
is nearly stable over the pH range 3.0–6.0 and 2.0–7.0
for CPE and PVC membrane electrodes, respectively. Selectivity
coefficient values towards different inorganic cations, sugars, and
amino acids reflect high selectivity of the prepared electrodes.
The electrodes responses at different temperatures were also
studied, and long operational lifetime of 12 and 5 weeks for CPE
and PVC membrane electrodes, respectively, were found. These are
used for determination of ketotifen fumarate using potentiometric
titration, calibration, and standard addition methods in pure
samples, its pharmaceutical preparations (Zaditen tablets), and
biological fluid (urine). The direct potentiometric determination
of KTF using the proposed sensors gave recoveries % of 98.97 ± 0.53 and 98.62 ± 0.74 with RSD 1.42 and 0.63% for CPE and PVC membrane selective electrodes, respectively. Validation of the method shows suitability of the proposed sensors for use in quality control assessment of KTF. The obtained results were in a good agreement with those obtained using the reported spectrophotometric method
A performance comparison of the contiguous allocation strategies in 3D mesh connected multicomputers
The performance of contiguous allocation strategies can be significantly affected by the distribution of job execution times. In this paper, the performance of the existing contiguous allocation strategies for 3D mesh multicomputers is re-visited in the context of heavy-tailed distributions (e.g., a Bounded Pareto distribution). The strategies are evaluated and compared using simulation experiments for both First-Come-First-Served (FCFS) and Shortest-Service-Demand (SSD) scheduling strategies under a variety of system loads and system sizes. The results show that the performance of the allocation strategies degrades considerably when job execution times follow a heavy-tailed distribution. Moreover, SSD copes much better than FCFS scheduling strategy in the presence of heavy-tailed job execution times. The results also show that the strategies that depend on a list of allocated sub-meshes for both allocation and deallocation have lower allocation overhead and deliver good system performance in terms of average turnaround time and mean system utilization
Group velocity control in the ultraviolet domain via interacting dark-state resonances
The propagation of a weak probe field in a laser-driven four-level atomic
system is investigated. We choose mercury as our model system, where the probe
transition is in the ultraviolet region. A high-resolution peak appears in the
optical spectra due to the presence of interacting dark resonances. We show
that this narrow peak leads to superluminal light propagation with strong
absorption, and thus by itself is only of limited interest. But if in addition
a weak incoherent pump field is applied to the probe transition, then the peak
structure can be changed such that both sub- and superluminal light propagation
or a negative group velocity can be achieved without absorption, controlled by
the incoherent pumping strength
Relativistic and Binding Energy Corrections to Direct Photon Production In Upsilon Decay
A systematic gauge-invariant method is used to calculate the rate for an
upsilon meson to decay inclusively into a prompt photon. An expansion is made
in the quark relative velocity v, which is a small natural parameter for heavy
quark systems. Inclusion of these O(v^2) corrections tends to increase the
photon rate in the middle z range and to lower it for larger z, a feature
supported by the data.Comment: 13 pages, LateX, One figure (to be published in Phys. Rev. D, Sept.
1, 1996
Inclusive dileptonic rare B decays with an extra generation of vector-like quarks
We investigate the leading effects of extending the Standard Model of
electroweak interactions by an extra iso-singlet up- and down- type quark pair
on various distributions and total branching ratio of the inclusive B-> X_s l^+
l^- (l =e,\mu) rare B decays. The presence of the extra vector-like down quark
results in the non-unitarity of the extended quark mixing matrix V, which
in turn leads to b-> s FCNC at the tree level proportional to (V^\dagger
V)_{sb}. On the other hand, the effective penguin and box vertex functions are
sensitive to the mass of the extra iso-singlet up quark m_U. The experimental
upper bound on BR(B-> X_s \mu^+ \mu^-) is used to constrain the parameters of
the model. It is shown that the shapes of the differential branching ratio and
forward-backward asymmetry distribution are very sensitive to the value of the
model parameters. We also calculate the CP aymmetry distribution of the
dileptonic decay in the vector-like quark model. It is shown that, for a
typical choice of the model parameters, asymmetries up to around 10% can be
achieved for certain values of the dilepton invariant mass.Comment: 15 pages, 2 figure
Instability and Fluctuations of Flux Lines with Point Impurities in a Parallel Current
A parallel current can destabilize a single flux line (FL), or an array of
FLs. We consider the effects of pinning by point impurities on this
instability. The presence of impurities destroys the long-range order of a flux
lattice, leading to the so called Bragg glass (BrG) phase. We first show that
the long-range topological order of the BrG is also destroyed by a parallel
current. Nonetheless, some degree of short-range order should remain, whose
destruction by thermal and impurity fluctuations, as well as the current, is
studied here. To this end, we employ a cage model for a single FL in the
presence of impurities and current, and study it analytically (by replica
variational methods), and numerically (using a transfer matrix technique). The
results are in good agreement, and in conjunction with a Lindemann criterion,
provide the boundary in the magnetic field--temperature plane for destruction
of short-range order. In all cases, we find that the addition of impurities or
current (singly or in combination) leads to further increase in equilibrium FL
fluctuations. Thus pinning to point impurities does not stabilize FLs in a
parallel current , although the onset of this instability is much delayed
due to large potential barriers that diverge as .Comment: 10 pages, 6 figure
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